Ventilation of a mine is typically controlled by fans and various structures in the mine that direct air flow for proper ventilation. Such structures include so-called “box checks” which restrict the flow of air past conveyors in the mine. Basically, a box check is a pair of parallel stoppings (walls) that are built across a mine entry. The stoppings are spaced apart a few feet and are basically identical. The space between the walls is the “box”. A conveyor belt passes through apertures in the two walls. The apertures should be fairly tight-fitting around the conveyor to limit the air flow through the apertures past the conveyor.
The stoppings of conventional box checks are typically made from concrete blocks, or brattice cloth, or metal panels of the type sold by Kennedy Metal Products and Buildings, Inc. which are jacked into pressure engagement with the roof and floor of a mine passageway. (These panels are described in various patents, including U.S. Pat. Nos. 4,483,642, 4,547,094, 4,820,081, 4,911,577, 6,379,084, 6,688,813, 6,846,132, and 7,267,505.) The stoppings have apertures to allow pass-through of a conveyor. The apertures may be framed with wood or other material to limit the flow of air past the conveyor. Conventional box checks are difficult to build and are easily damaged by things going wrong with the belt (e.g., the belt moving off track and touching the frame; the heap on the conveyor becoming too high; and break-down of the conveyor structure). Further, the performance of such box checks generally fails to meet expectations. That is, they fail to properly limit the flow of air past the conveyor belt.
There is a need, therefore, for an improved box check for a conveyor belt.